Corrosion prevention



Patented Aug. 14, 1945 CORROSION PREVENTIO Herbert D. Rhodes and RogerW. Watson, Chicago, 111., asslgnors to Standard Oil Company, Chicago,lill., a corporation of Indiana No Drawing. Application December 21,1942, Serial No. 469,702

13 Claims. 101. 25241) The present invention relates to compositionspossessing corrosion or rusting preventive properties. More particularlythe invention relates to the use of certain corrosion or rust inhibitorsin compositions containing predominately hydrocarbon or non-hydrocarbonmaterials, in connection with the use of suchcompositions in systemsemploying water or steam, or which may become contaminated with water orsteam.

In various industrial equipment in which water or steam is used or whichmay become contaminated with water or steam during service, rusting orcorrosion of themetal parts, particularly the ferrous metal parts, isencountered causing material damage to such equipment. For example, inthe operation of steam turbines rusting or corrosion of the metal partsof such systems is a serious problem and hence the prevention orinhibition oi such corrosion or rusting is highly important.

It is, therefore, an object of the present invention to providecompositions which will effectively inhibit or prevent the rusting orcorrosion of metal parts of equipment which come in contact with wateror steam. It is another object of the present invention to provide anoil composition which will effectively inhibit or prevent rusting orcorrosion in systems in which oil is brought in contact with water orsteam. Another object of the invention is to provide means of preventingrusting or corrosion to metal parts of equipment in which water or steamis used or which may become contaminated with water or steam. Stillanother object of the invention is to provide a lubricant compositionwhich effectively inhibits or amounts for example, from about 0.001% toabout 0.5% and preferably from about 0.005% to about 0.1% otahydroxylamine or an organic salt of hydroxylamine having the followingrepresentative formulae:

N 8H R t and o R"C ONRt OH in which R and R are substltuents selectedfrom the group consisting of hydrogen, avhydrocarbon substituent and anester residue and R" and R are substituentsselected from the groupconsisting of hydrogen and a hydrocarbon substituent. When R, R, R" andR' are hydrocarbon substituents such as aliphatic radicals, (i. e. alkyland alicyclic radicals), aryl radicals, alkaryl radicals, arylalkylradicals, etc., they may bethe same or different substituents, and arepreferably of sufficient size to render the compound oil soluble, forexample, a long chain parafiinic hydrocarbon. Examples of specificcompounds of the above named classes are the following:

N lauryl hydroxylamine Naphthenic acid salt of hydroxylamine Waxsubstituted hydroxylamine Methyl naphthenate substituted hydroxylamine Nbutyl hydroxylamine Octyl hydroxylamine Cetyl hydroxylamine,

Lauryl hydroxylamine salt degree corrosion or rust inhibiting propertiesall or them are not necessarily equivalent in.i;heir effectiveness.

We are aware that hydroxylamines hav been used in lubricants to impartextreme pressure properties thereto. For example, U. 8; Patent 2,066,173discloses the use of hydroxylamines in combination with various nitroaromatic compounds to impart extreme pressure properties to lubricantsand to retard wearing and seizure of bearing surfaces. The presentinvention is not concerned with the lubricating properties oflubricating compositions but is concerned with the inhibition of rustingor corrosion of metal surfaces which come in contact with water. Ourinvention is particularly adapted to equipment or systems in which alubricant and an aqueous material are employed, or in systems employinga lubricant in which contamination by water may be encountered. In suchsystems rusting is prevented or inhibited by employing a lubricantcontaining small amounts of a hydroxylamine or an organic salt ofhydroxylamine of the type above described. For example, in the operationof steam turbines rusting or corrosion of those portions of theequipment which come in contact with water or moisture is substantiallyprevented or inhibited by employing a turbine oil to which has beenadded a small amount of a hydroxylamine or an organic salt of ahydroxylamine. 1

For the purpose of exemplifying our invention, th same will be describedas applied to steam turbine lubrication, for which highly refined oilshaving Saybolt Universal viscosities at 100 F. of from about 125 secondsto about 350 seconds are employed, although it is to be understood thatthe invention is not limited thereto. With the advent of drasticrefining treatments to produce more highly refined turbine oils havingimproved sludging resistant and emulsiflcation properties, the desirablecomponents of oils responsible for the wetting and thereforerust-inhibiting qualities of the oil were, however, removed by theserefining methods and the stable oils produced became inferior withrespect to rust-inhibiting qualities. In steam turbines, rusting isusually encountered in the upper portions of oil reservoirs, and otherparts of the system caused by droplets of water coming in contact withthe steel surfaces which have been covered by the oil and displacing it.An oil will provide adequate protection against this rusting only if itwets the steel surfaces preferentially as compared with water. In thepresence of oils which provide no protection coating, the steel surfacesare attacked by water with the formation of ferric oxide and blackmagnetic oxide. As the rusting progresses these oxides scale oil and maybe carried in suspension in the oil, often scoring bearings, pluggingoil lines and often causing faulty operation or sticking of delicategovernor parts. The need for non-rusting turbine oils is thereforegreat.

In accordance with the present invention the addition of small amountsof hydroxylamines or organic salts thereof to turbine oils eflectivelyinhibits rusting of the type above described. The rust-inhibitingcharacteristic of turbine oils containing these additives isdemonstrated by the following test: Three hundred cubic centimeters ofthe oil to be tested are placed in a 400 cc. lipless glass beaker andheated to about 140 F. in an oil bath and the oil stirred with a stirrermaintained at about 750 R. P. M. When the temperature of the oil samplereaches about 140 F. a cleaned test strip of cold-rolled steel isBillspended in the oil and stirring continued for 30 minutes to insurecomplete wetting of the steel specimen. Thirty cubic centimeters ofdistilled water are then carefully added by pouring it down the side ofthe beaker, and stirring continued for 48 hours. At the end of thisperiod the specimen is removed from th beaker, washed with naphtha andvisually inspected for the presence of rust. The method of carrying outthis test is fully described in the ASTM Manual 1942, page 274, andidentified as ASTMX mess-42 A number of oils containingvarioushydroxylamines and salts of hydroxylamines were subjected to theabove test, and the'following 'results Test pieces are rated numerically1 to 5 accordin to increasing amounts of corrosion. A rating of 1 is gven test pieces showing no rust or discoloration; a rating of i5 is ivento badly rusted test pieces resulting from tests on unin ibited oils.

To inhibit the oxidative deterioration of the oils susceptible to suchdeterioration small amounts of known antioxidants can be added to theoils in combination with the hydroxylamines or their organic salts, forexample, catechol, tertiary butyl catechol and octyl catechol can beused. Other effective antioxidants are cresol, pyrogallol, hydroquinol,and hydroxy condensed ring compounds and their alkyl derivatives, suchas beta-naphthol, octyl beta-naphthol, amyl betanaphthol, laurylbeta-naphthol, alpha-naphthol. cetyl alpha-naphthol, amyl alpha-naphtholand other alkyl derivatives of betaand alpha-naphthols. Otherantioxidants such as phenyl alphanaphthylamine, diphenylamine, butylpara-aminophenol, etc., can be used. The amount of antioxidant employedwill depend upon the effectiveness of the particular material used, butin general will range in quantity from about 0.001% to about 0.25%.Thus, we have found that a suitable turbine oil having a SayboltUniversal viscosity at F. of from about seconds to about 330 secondsexhibiting non-rusting properties and resistant to oxidativedeterioration is onecontaining from about .0005% to about .1%

wax substituted hydroxylamine and from about 0.02% to about 0.2% of amixture containing two parts of beta-naphthol and one part of octylbetanaphthol.

While we have described our invention by reference to its adaptabilityto turbine oils, it is to be understood that this is intended to bemerely illustrative of the invention and not a limitation of .the scopethereof. Thus, our invention is applicable to emulsiilable soluble oils,liquid fuels, greases, and in general to compositions in connection withwhich the water-corrosion of the containing system is to be avoided.

We claim:

1. A rust inhibiting oil composition adapted for use in the presence ofwater in systems containing metal susceptible to corrosion by said watercomprising an oil and a hydroxylalmine compound selected from the groupconsisting of a hydroxylamine having the general formula in which R andR are substituents selected from r the group consisting of hydrogen, ahydrocarbon substituent and an ester residue and a salt of hydroxylaminehaving the general formula rw-cf omw 'orl in which R" and R' aresubstituents selected from the grou consisting of hydrogen and ahydrocarbon substituent, said hydroxylamine compound being used in smallbut suflicient quantity to inhibit the corrosion of said metal.

2. A rust inhibiting oil composition adapted for use in the presence ofwater in systems containing metal susceptible to corrosion by saidwater, comprising an oil and an aliphatic substituted hy-,

' droxylamine having the general formula in which at least one of theR's is an aliphatic group, said aliphatic substituted hydroxylaminebeing used in small but suflicient quantities to inhibit the corrosionof said metal.

3. A rust inhibiting oil composition adapted for use in the presence ofwater in systems containing metal susceptible to corrosion by said watercomprising an oil and an organic salt of hybut suillcient quantity toinhibit corrosion of said metal.

'7. A rust inhibiting oil composition adapted for use in the presence ofwater in systems containing metal susceptible to corrosion by said watercomprising an oil and a methylnaphthenate substituted hydroxylamine inwhich the hydroxyl radical is attached directly to the nitrogen atom,said methylnaphthenate substituted hydroxylamine being used in small butsufiicient quantity I to inhibit the corrosion of said metal.

droxylamine in which the hydroxyl radical is attached directly to thenitrogen atom, said organic salt of hydroxylamine being used in smallbut suillcient quantities to inhibit the corrosion of said metal.

4. A rust inhibiting oil composition adapted for use in the presence ofwater in systems containing metal susceptible to corrosion by said watercomprising an oil and a wax substituted hydroxylamine, having thegeneral formula in which at least one of the R's is a wax substituent,said wax substituted hydroxylamine being used in small but sufficientquantity to inhibit the corrosion of said metal.

5. A rust inhibiting oil composition adapted for use in the presence ofwater in systems containing metal susceptible to corrosion by said watercomprising an oil and .a naphthenic acid salt of hydroxylamine in whichthe hydroxyl radical is attached directly to the nitrogen atom, saidnaphthenic acid salt of hydroxylamine being used in small but sufficientquantity to inhibit corrosion of said metal.

6. A rustinhibiting oil composition adapted for use in the presence ofwater in systems containing metal susceptible to corrosionby said watercomprising an oil and a lauryl hydroxylamine having the general formulain which at least one of the R's is a lauryl group,

said lauryl hydroxylamine being used in small 8. In a system in which onand water are present and in which metal surfaces of said system aresusceptible to corrosion by said water,the method of inhibiting saidcorrsion comprising employing in said system an oil containing a smallamount of a hydroxylamine compound selected from the group consisting ofhydroxylamine having the general formula in which R and R aresubstituents selected from the group consisting of hydrogen/ahydrocarbon and an ester residue and a salt of hydroxylamine having thegeneral formula rw-c oNnw' on in which R" and R'" are substituentsselected from the group consisting of hydrogen and a,

lip-0 in which R" and R' are substituents selected from the groupconsisting of hydrogen and a hydrocarbon substituent.

10. A stabilized and rust inhibiting turbine lubricant comprising amineral oil, and in combination a small amount of an antioxidantsufllcient to inhibit the oxidation of said mineral oil and a smallamount of a hydroxylamine compound selected from the group consisting ofa lhydroxylamine having the general formula N-OH R! in which R and R aresubstituents selected from the group consisting of hydrogen, ahydrocarbon and an ester residue, and a salt of hydroxylamine having thegeneral formula V oNal'" OH in which R" and R' are substituents selectedfrom the group consisting of hydrogen and a hy- 4- a,eao,s1a

0.0005% to about 0.1% of a hydroxylamine in 1 the nitrogen atom. v

13. A ltabiliied and rust inhibiting turbine oil comprising a mineraloil. from about 0.001% to about 0.25% or a beta nephthol and from about0.0005% to about 0.1% of a salt of hydroxylamine in which the hydroxylradical is attached direct- 18 to the nitrogen atom.

' HERBERT D. RHODES.

ROGER W. WATSON.

which a hydroxyl radical u m nia directly to

